I have a 94 buick lesabre w/ 3.8L eng.

I has 120,000 miles and has knocked since 90,000 with no loss in power (except for hesitation) and knock does not appear worse (apparently piston rod bearing), also does not burn oil. Recently, alternator and battery was replaced.

Took it to mechanic because it hesitated moderately, chk eng. Lite came on and off. Ran codes and found no specific reading, replaced egr and egr gasket, checked for vacuum leaks, replaced eng. Computer. Car hesitates worse than ever, battery gauge light flashes on when needle is at about 14.5, and car shuts off while driving.

Mech. Says that it is probably the engine sensors (knock or c shaft sensors) that are telling the computer to make compensations to certain devices (or something like that), which may be causing all the problems. Therefore the engine needs replaced/rebuilt or get a new car.

My question is: Is there something else that he may not be aware of that is causing this? Maybe the computer that controls the car's electrical components? Tell me something good. We love the car.

Thanks

Thoughts:

. Consider changing oil weight to dampen connecting rod knock.
. Engine dying may be a function of the Ignition Control Module being bad. AutoZone can test ICMs and coils for free.
. Use a mechanic's stethoscope or large-handle screwdriver to positively identify where the knock is coming from.
. See if the knock lessens with high octane gas.
. Replace spark plugs and see if the situation improves.
. Check for codes again--if the situation is as bad as presented, one or more codes should be thrown. That should definitely point you in the right direction.

First, if the car hesitates worse now than before, I'd have him take the computer out of the car and off my bill.
Not to say the computer isn't your problem, just the one he's offering may be worse. You are not supposed to make it worse!
The problem could be a myriad of different things: ignition system, fuel system, electronic components... the engine computer may be bad. Too much to keep on a short list.
There is also a good chance the crankshaft position sensor is on the verge of failure, but the fuel pressure needs to be monitored when the engine does stall. That is about the only way to "see" the fuel pump fail.
If your current mechanic can't diag your car, find another mechanic. Stick with your car!